If you were writing a top-five list of Dalek shortcomings, having to make do with a glorified plunger for a hand might rate pretty high on the list. Turns out, though, that might actually be a high-point of robotics evolution; a team at the University of Chicago in Illinois has bypassed complex, tricky-to-control robotic fingers by using a pliable rubber sack filled with coffee grains or glass spheres, and which can be used to grip objects by adjusting the internal pressure.
In fact, a simple 1-percent reduction in internal volume is sufficient for the gripper to take hold of an object; as long as around one-fourth of the object's surface area can be enveloped, that's sufficient. With no individual fingers to control, and increased flexibility as to how the gripper approaches the object, it's a far more straightforward way to pick things up.
Right now there are limitations: porous or flat objects are trickier to grab than unusually-shaped ones, and the grabber can only hold something half its size or smaller. Still, the team expect the research to be useful in developing prosthetic limbs for amputees.